Taxonomy

Lecanopteris is in the large global family, Polypodiaceae. 13 species of Lecanopteris are currently recognised.

Lecanopteris has been split by some researchers into 2 genera (or into 2 sections of Lecanopteris) on the basis of 2 main features:

Myrmecopteris has

rhizome clothed with distinctive scales

sori (clusters of spore capsules) that are not marginal

Lecanopteris has

rhizome that is not scaly

sori on reflexed marginal lobes of the frond

L. spinosa is intermediate between these 2 groups, having no scales but with sori not marginal. Thus its discovery supported the recognition of a single genus.

Subsequent research suggested that since Myrmecopteris seemed to be closely related to the genus Phymatodes, Lecanopteris in the broad sense could not be monophyletic and the 2 subgenera might have had different origins. However, more recent DNA studies support Lecanopteris as a monophyletic genus comprising closely related species derived from a common ancestor.

pale green and glaucous when young, becoming black with age and without stomata

grows continuously and dies back at the other end

grows in 3 to 4 superimposed layers around a branch to form a ball-like clump up to 25cm across

densely covered with strong spines up to 6mm long

glabrous - lacks scales or hairs except when very young

hollow - as it ages the pith cells in the centre dry out and shrink to form cavities exploited by ants

The morphology and internal structure of the rhizome varies in complexity according to the species. Most have a single gallery running through the rhizome and into the side branches but a few, including Lecanopteris spinosa, have a much more complex system of interconnecting galleries and chambers.

The fronds are:

simple (sterile fronds) or lobed (fertile fronds)

more-or-less sessile (not stalked)

jointed to rhizome

lamina (leaf blade) up to 30cm long and 3 to 4cm wide

leathery

glabrous

The sori are:

round

in 1 row on either side of the rachis (midrib)

deeply immersed in the frond so they project on the upper surface

naked, having no protective indusium - a characteristic of the Polypodiaceae

Look-alikes

Lecanopteris spinosa is unlikely to be confused with other species of Lecanopteris due to its unique combination of characters: